The invention relates to a dialysis machine and a process for its disinfection.
Dialysis machines must be disinfected and/or made as sterile as possible before each use.
German Patent 31 15 665 describes a hemodialysis device with a dialysis container for the storage and reception of dialysis liquid. The disclosed device is operated in such a way that, within the framework of the dialysis treatment, the dialysis liquid is not discarded after passing through the membrane unit of the dialyzer, but led back to the dialysis container. The problem of possible multiplication of micro-organisms in the solution is effectively confronted by providing a UV radiation source which sterilizes the dialysis liquid before and, when necessary, for some time after the start of the treatment. In order to achieve as uniform as possible an effect of the UV treatment, the UV radiation source is introduced into a pipe located in the container that is arranged concentrically in the dialysis container or in an influx pipe for the used dialysis liquid located centrally in the container. Provided for this are materials with sufficient UV permeability between the UV radiation source and the liquid to be sterilized. The radiation at the start of and possibly for some time after the treatment has begun has the effect of being able to keep the dialysis liquid essentially sterile for the entire duration of the treatment. A further possibility of sterilizing the liquid located in the dialysis container consists of preferably arranging an infrared heat radiation attachment underneath the dialysis container by means of which the liquid located in the dialysis container can be heated for the purpose of sterilization. With a suitable design of the container, a temperature of 110xc2x0 C., favorable for the purpose of sterilization, can be reached. A disadvantage of such a sterilization system is that essentially only the liquid located in the dialysis container is sterilized, whereas direct cleaning of the pipes and other structural components distant from it is not possible.
In U.S. Pat. No. 5,336,165 a dialysis machine is disclosed with which automated cleaning and disinfecting liquids can be prepared and, after termination of the dialysis treatment, stored in different lines and circuits. The solvent used for the corresponding chemicals is water, which is cleaned and sterilized before it is used. Cleaning and sterilization is effected by means of filters and membranes, a deionization device, as well as with the aid of a UV radiation source. After the end of the dialysis process, the cleaning solution is prepared by conveying the cleaned, sterilized, and prewarmed water into a chamber containing the cleaning and disinfecting chemicals which is closed during the treatment of the patient. During the procedure of dissolving the chemicals, the mixture is led into the circulation until complete dissolution is indicated with the help of conductivity probes. Cleaning of the lines as well as of the dialyzer itself is effected by reversing suitable valves following the dissolution procedure. In so doing, part of the substances contained in the cleaning solution goes over to the side of the blood circulation in accordance with the concentration gradient across the membrane of the dialyzer until a concentration balance occurs. After termination of the cleaning process, a cleaning solution of low concentration is pumped over to both the dialyzer side and the blood side until the beginning of a renewed dialysis treatment, which correspondingly inhibits microbial growth between two treatment cycles.
The drawback of such a dialysis device is that the required cleaning and/or disinfecting agents must be supplied from the outside in a condition ready for use, for example in solid or highly concentrated liquid form.
This leads to high transportation and packaging costs. Furthermore, the required disinfecting agents thus become dependent on actual availability. Moreover, the handling of such materials is possible only if there is due regard for special precautionary measures because, as a rule, aggressive, corrosive substances are involved. Also, the packaging material used for the delivery of these substances must be disposed of as waste. But the transportation problems have proven to be especially cost-intensive in practice.
The active substance most widely used worldwide for the disinfection of dialysis machines is NaOCl (bleach). However, with this highly effective disinfecting and bleaching agent, environmental pollution is especially great. On the other hand, NaOCl has the advantages of simple handling and effective cleaning/disinfection. Furthermore, in many states NaOCl is often the only disinfecting agent available.
Yet there are also other disinfecting agents in widespread use, such as, for example, peracetic acid, hydrogen peroxide, citric acid or ozone.
The object of the invention is to make available a dialysis machine that is not dependent on the delivery of the disinfecting agent.
The object of the invention is achieved by a dialysis machine having means for generating at least one disinfecting agent that can be used for disinfecting the dialysis machine. Alternatively, the invention provides a process for disinfecting a dialysis machine using a disinfecting agent wherein at least one disinfecting agent is generated on line and the disinfecting agent is brought into contact with the dialysis machine.
With the dialysis machine according to the invention, and/or the process according to the invention, it is now possible for the first time to operate dialysis devices largely independently of the availability of ready-to-use disinfecting agents, which leads to considerable savings in transportation and packaging costs. Waste disposal of the packaging materials usually required as well as long and dangerous transportation of chemicals are eliminated. In addition, far greater handling advantages accrue to the operator.
Moreover, operating safety is enhanced to the extent that dealing with aggressive, corrosive substances is largely avoided.
According to one advantageous embodiment, the dialysis machine has means for decomposing the disinfecting agent generated on line into environmentally compatible decomposition products. This ensures that after their use disinfecting agents harmful to the environment do not enter the sewage and/or the outside world.
According to one embodiment, the dialysis machine has a pipe system through which the decomposition products formed during the decomposition of at least one of the disinfecting agents, which decomposition products are reusable for the on-line generation of disinfecting agents, can be reconveyed back to the means for the on-line generation of disinfecting agents. This creates a closed recycling circuit for the production of disinfecting agents.
According to one preferred embodiment, the dialysis machine has an NaOCl generator, which produces sodium hypochlorite (NaOCl) by electrolysis of NaCl. Especially preferred for this is the use of NaCl contained in the dialysate concentrate.
In accordance with another advantageous embodiment, the dialysis machine according to the invention has a lead oxide anode for the production of ozone by electrolysis of oxygen.
According to another advantageous embodiment, a UV photo-oxidation attachment is provided by means of which UV photo-oxidation of water can be carried out. It is also possible to expose a dialysis concentrate or also a ready-to-use dialysate to UV photo-oxidation. Oxygen dissolved in water, for example, is thereby converted into ozone. Such ozone has a germicidal effect and can thus be used for the production of sterile water.
The sterile water thus produced can be added to the disinfection liquid. As a rule, it is assumed that the ozone produced by UV photo-oxidation will be used together with additional ozone.
However, the sterile water is not necessary during disinfection. Its use is to be seen, primarily, in the rerinsing operation, but also in the production of a substitute for hemofiltration and hemodialysis filtration from ultrapure water, since the latter is directly infused into the patient. Furthermore, dialysate can be produced ultrapure or, for example, supplied in advance to the blood circulation via the dialyzer.
The sterile water produced by UV photo-oxidation can also be used as rinse water, by means of which disinfecting agent residues can be removed from the dialysis machine after completion of the disinfection operation. The production of ozone in the precleaned water ensures that no recontamination of the dialysis machine by the rinse water can occur during the clean-rinsing operation.
It is possible to convert water produced by reverse osmosis (RO water) into ultrapure water. Any desired disinfecting agent can then, for example, be added to this ultrapure water, thereby ensuring optimal disinfection of the dialysis machine. As mentioned, the ultrapure water thus produced can then be used as rinse water. Furthermore, it can be used in the subsequent dialysis for the dilution of a dialysis solution concentrate with which ultrapure dialysate can be prepared.
When NaOCl is used as disinfecting agent, the dialysis machine has, according to one advantageous embodiment, a catalyst for the catalytic decomposition of NaOCl into NaCl and oxygen.
The NaCl thus formed can either be led into the waste water, thereby strongly reducing the pollution thereof, or, in accordance with another embodiment, again conveyed to the NaOCl generator.
According to another advantageous embodiment, the dialysis machine also has a device for determination of the content of disinfecting agent in the disinfection liquid used or in a rinsing liquid used thereafter.
This device for determination of the content of disinfecting agent is preferably a redox electrode. This can, for one thing, ensure that disinfecting agent is actually available and, for another, test whether disinfecting agent is still present in the dialysate circulation after the clean-rinsing operation. Such a redox electrode can easily be incorporated into a dialysis machine.
The determination of the content of disinfecting agent through the redox potential of the disinfection liquid, the rinsing liquid and/or the dialysis solution used during the actual dialysis, represents another simple and reliable procedure. The measured value indicated by the redox electrode can be advantageously used as control variable for control of the rinsing and catalysis operation.